To get started with codeless mobile Event tracking, click the Settings gear in the upper righthand corner of your Mixpanel project and select Autotrack from the dropdown:
Then choose your platform, and connect your app using either a phone or an emulator. Once you’re connected, you can easily add Event tracking to your app from your browser.
Note that with codeless mobile tracking, you can track Events but will not have the ability to add custom Properties to those Events. To get the full value out of Mixpanel and be able to slice and dice your data by custom Properties, the general recommendation is to use codeless mobile tracking in tandem with traditional Mixpanel tracking (iOS and Android).